Xylitol-producing biorefinery from sugarcane: new strategies to make the biotechnological route viable

Abstract

Results from ongoing and recent research at EEL-USP (FAPESP: Processes 2013/27142-0 and 2016/22179-0) point to the technical feasibility of the biotechnological route for xylitol production by Candida guilliermondii FTI 20037 (recently identified as C. tropicalis) with the concomitant use of sugarcane bagasse and straw. However, there are still bottlenecks to be solved, such as the simplification and/or improvement of process steps, understanding of physiological and/or molecular aspects, combined with the study of technical and economic feasibility. Thus, this project aims to optimize the dilute acid hydrolysis conditions for the mixture of bagasse and straw, to evaluate the detoxification step of the hemicellulosic hydrolyzate by yeast adaptation and/or replacement of the use of active charcoal by the residual yeast biomass from the fermentative stage. Also, a new approach will be the study of the effects of toxic compounds by flow cytometry, allowing to evaluate the viability, complexity and cellular metabolic state, and molecular biology tools will be applied to study the transport mechanisms involved in xylose consumption. Furthermore, a cross-sectional approach and in cooperation with the "Grupo de Diseño de Produtos y Procesos" of the Universidad de Los Andes (Bogota, Colombia) will be the establishment of a platform for virtual simulation of the biotechnological xylitol production route for technical and economic analysis of the bioprocess. Results of this project are expected to contribute to the technical and economic feasibility of xylitol bioproduction through the joint use of sugarcane agroindustry byproducts, such as bagasse, straw and molasses, promoting integration in a sugarcane biorefinery in the context of the bioeconomy. (AU)